This is a printable linear bearing / bushing. It has the exact same dimensions as a LM8UU (8mm ID, 15mm OD, 24mm length) so it is a drop-in replacement.

I designed this bearing for two reasons: to eliminate the noise created by the generic LM8UU bearings, and to serve as a replacement for the ones that wore out / lost balls.

The design doesn't have any printer-specific tolerances incorporated into it (that is, the inner diameter in the STL is exactly 8mm). When you print it, if you find that the bearing is too loose and that there is noticeable play, then you can scale it down in the X and Y directions. If instead you find that it is too tight (which is more likely to happen), while you could similarly scale it up, I found that the best solution was to run an M8 threaded rod through the bearing. This allows you to smooth out and expand the inner diameter until the bearing slides just right on the smooth rod.

The ideal way to attach the bearing to your printer would be to tightly press it into a mounting block, so that it is under even pressure from all directions. However, simply using zip ties works as well. I used zip ties when attaching these to my current printer, and while this makes the bearings become tighter on the smooth rods, they can still move good enough.